1. Field of the Invention
The present invention relates to a two-liquid type mixer for mixing two liquid materials to form a resin material, and for applying or injecting the resin material from the mixer.
2. Description of the Related Art
Silicon resins are known to be of a two-liquid type wherein liquids A and B are mixed in a mixer to form a mixed liquid which is discharged from a nozzle defining the forward end of a mixer which may have a hollow cylindrical shape.
FIGS. 8 and 9 are illustrations of conventional mixers. A mixer MX1 as depicted in FIG. 8 includes a rotor 3 connected to a driving source (not shown) and disposed rotatably in a casing 2 having a hollow cylindrical chamber and a nozzle 1 at a tip thereof. In this mixer MX1, the two liquids A and B are fed under pressure through channels 4A and 4B which are provided at an upper end of the mixer MX1. A screw for feeding the two liquids A and B under pressure may be provided above the rotor 3, as required. Since rotor 3 rotates in the chamber within the casing 2, the two liquids A and B are agitated appropriately for discharge through nozzle 1.
In the hollow cylindrical mixer MX2 depicted in FIG. 9, blade assemblies 3A of the rotor 3 are arranged at equal distances along the rotor and projections 6 projecting from an inner wall surface of the casing 2 are alternately disposed between adjacent ones of the blade assemblies 3A. These projections 6 prevent the mixed liquid from flowing in an unobstructed manner along the wall surface of the chamber 2.
With conventional mixers MX1 and MX2, however, the following drawbacks have been encountered.
First, with reference to mixer MX1, since a passage which allows the mixed liquid to flow therethrough is formed along the inner wall surface of casing 2, a partially unmixed liquid is discharged from the nozzle 1, irrespective of positioning of rotor 3. Accordingly, this mixer is difficult to use where sufficient mixing is required (e.g., mixing a resin with a foaming agent).
With reference to mixer MX2, although the above-described direct flow of the mixed liquid in an unobstructed manner is prevented slightly by means of the projections 6 provided on the inner wall surface of the casing 2, this structure merely prevents the direct flow of the mixed liquid in an unobstructed manner along the inner wall surface of the chamber 2. When seen in a plan view, a large gap is always present between the blade assembly 3A of the rotor 3 and the projection 6. Hence, mixer MX2 unavoidably discharges an incompletely mixed mixture.
If two liquids constituting a foaming silicone resin are mixed with either mixer MX1 or MX2 and the mixture is then allowed to foam, foaming becomes incomplete due to incomplete mixing, so that a continuous foam F1 of a mottled pattern is formed, as depicted in FIG. 10. In addition, since foamed particles gather and the surface becomes hardened, the product becomes defective, so that it is difficult to obtain a foam F2 having proper closed bubbles, such as the foam in FIG. 11.
Furthermore, since the above-described mixers MX1 and MX2 are arranged to perform the liquid agitating action based on the rotation of the rotor 3, the number of revolutions becomes large (e.g., 2400 rpm). Hence, there is a problem of high heat generation which accelerates curing in the case of a thermosetting resin. Excessively large cooling equipment is required to prevent both premature curing and early foaming in the case of a foaming resin.
These various problems tend to be promoted as the viscosity of the mixed liquid becomes high. This is attributable to the fact that as the viscosity becomes high, the mixed liquid rotates with the rotor, thereby making it impossible to effect sufficient mixing.